ABOUT
Your conversations should be answerable. And they should stay private.
Lembic is a small Mac app with one job: turn an iMessage thread into a clean, AI-ready file you can hand to your own ChatGPT, Claude, or Gemini, without it ever leaving your machine.
WHY I BUILT THIS
It started with one person in my family.
She's going through a hard divorce, and the other person will only communicate one way: by iMessage. To keep her footing in those conversations, and to keep an eye on her own tone, she'd been copying messages back and forth between Messages and ChatGPT, one at a time.
She asked me a simple question: could she just give ChatGPT their whole history at once, so it understood the full pattern of how he talks to her? I went looking. Everything I found cost real money or took real technical skill. There was no simple, private way to take a conversation and hand it to an AI, so I built one.
For messages like hers, privacy isn't a nice-to-have. The last place those texts should end up is on some company's server.
What I'm building, and what I won't.
One Mac app that does a single thing well: a clean, compact, AI-ready transcript. No PDFs, no Terminal, no bloat. These are the lines the app is built not to cross.
Private by architecture
There's no backend. Your messages never leave your Mac, because there's nowhere for them to go.
Open-source engine
The code that reads your messages is open source. Don't take my word for it. Read it yourself.
Bring your own AI
Use the ChatGPT, Claude, or Gemini account you already pay for. No middleman model in between.
Pay once
A one-time purchase, not a subscription. No lock-in, no recurring charge, no upsell.
THE FOUNDER
One person stands behind this.
Darec Stowell
Founder & sole developer, Lembic
I'm a software engineer building this on my own. No team to hide behind, no investors to answer to, no data to resell. If the privacy promise ever broke, it would be on me, so I built the app so that it can't break. The engine is open source for that exact reason: you don't have to trust me, you can read the code.
Your messages, finally answerable.
Lembic is launching soon. Join the waitlist for early access and the one-time launch price.
100% on-device · open-source engine · bring your own AI